New Grinder build. help?


Well-Known Member
No wiring difference - the supply voltage determines the wiring connections. The RPM depends on the number of poles in motor and frequency of supply. The theoretical rpm of a motor is hertz times number of seconds in a minute times two (60X60X2 = 7200) then divide 7200 by number of poles in motor. 7200/4 poles = 1800 rpm (or 3600 for a 2 pole motor). Now, the actual rpm the motor will give depends on the slippage incurred by the motor and that will vary a bit from manuf to manuf. That's why you'll see 1725 or 1750 rpm on name tag. The 1800 (or 3600) is the theoretical calculated rpm.

There should be a parameter setting in your VFD that determines the max frequency in hertz the VFD will output.

Daniel Macina

Well-Known Member
There is a little red jumper that you put in a different spot to get x2 speed. It's on the upper right side if I remember correctly. The manual is very good though so be sure to read that.


Well-Known Member
Daniel, the jumper is for the KBAC drives. He's ordered a Telco drive and I don't remember if it uses a jumper or a parameter setting to double RPM. The Chinese drives I use have a parameter to change allowing the freq to be set at 60 hz, 70 hz, or any value desired with a max of (I think) 400 hz.
I have a 1 hp Telco drive and parameter 07 sets the upper frequency limit with a max of 200 hz. I'm not sure how the model the OP has will work.

I just checked the manual for the Telco drive he ordered. Looks like parameter 00-12 on page 4-9 shows the max freq at 599 mhz. The max freq can be set anywhere between 0.01 and 599.0 hz using that parameter.
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